ME7 Idle; solved = better braking, improved economy
 

Hi peeps

Thought I would share my findings :)

Just for history; I have had a bad idle since I have had the car, fluctuating +/- 100 rpm, occasional hesitation and stalling. The car has had 3 ETMs each resulting in the same idle result.

I have discovered the root cause for this fault: a failed non-return valve on the EVAP system (pollution control).

This was allowing a direct air leak at idle from the inlet piping to the manifold.

Testing involves "sucking and seeing" lol; remove the pipe from the inlet tube and you should be able to suck, but not blow.

To remedy this, I inserted an extra non-return valve (as I am on a budget and didn't fancy paying £48 + vat from Volvo). The OEM valves also acts as a reducer, hence my reason for keeping it.

Results are SOLID IDLE (glourious to me as this has been a pain in 2 years ownership and £££s), better braking power (due to increased manifold vacuum under engine braking) and I have already seen a marked improvement in MPG (I used to see 230 to a tank normal driving. After running the tank dry from half a tank with the fixed leak, I am seeing 260 :) I'll report back how many miles from a full tank!)

Hope this helps some peeps and it's really quick to check out.

Chris

Nice one Chris, attention to detail always pays off in the long run.

Had you also noticed a problem when braking when you had the problem? Could this also affect my S40 2.0T as you symptoms sound similar to what I get occasionally.
Chris

My 2.0 S40 2001my non turbo has a similar set up so worth checking out mate. :)

Yes, occasionally overlight and no real confidence approaching bends in gear; when the idle had a fit of idle hiccups, I could feel the brake pedal soften a lot; this is when the lightbuld lit up in my head (traffic is good for something I guess!)

Chris

Where did you get the extra non return and where does it go?
Thanks for the info.
Chris

Hi there

Luckily I had a suitable one at home. I've visited several autofactors and non were ANY help, lol.

I reckon they can be bought from Volvo reasonably - the parts guy I had was totally useless.

I have also seen some on EBay that would work.

Chris